Why does the body need sodium?
Simple, the sodium regulates water by binding to it in your blood cells. If there is too much, your blood cells will enlarge, if there is too little, your blood cells will shrink.
Sodium is an element which attracts water. Wherever sodium goes, water will always follow which is why people who are dehydrated or are suffering from low sodium will suffer from spasms , cramps, seizure or possibly coma.